Abstract

The cryptochromes are a family of blue light photoreceptors that play important roles in the control of
plant development. We have characterised the cryptochrome gene family in the model legume garden pea
(Pisum sativum L.). Pea contains three expressed cryptochrome genes; a single CRY1 orthologue, and two
distinct CRY2 genes that we have termed CRY2a and CRY2b. Genomic southern blots indicate that there
are unlikely to be more CRY genes in pea. Each of the three genes encodes a full-length CRY protein that
contains all the major domains characteristic of other higher plant cryptochromes. Database searches have
identified Medicago truncatula expressed sequence tags (ESTs) corresponding to all three genes, whereas
only a single CRY2 is represented in EST collections from the more distantly related legumes soybean and
Lotus japonicus. The proteins encoded by the pea and Medicago CRY2b genes are distinguished from other
CRY2 proteins by their shorter C-terminus. Expression analyses have identified marked differences in the
regulation of the three genes, with CRY2b expression in particular distinguished by high-amplitude diurnal
cycling and rapid repression in seedlings transferred from darkness to blue light.